This invention relates to communication system call tracking control arrangements and more particularly to an arrangement for controlling the tracking feature in a stored program controlled communication system.
In communication systems where the users share a community of interest, as for example in a business communication system, it often happens that a call is placed to a station where the user is busy with another communication call. In some systems it is possible that the second call will result in ringing, or other signalling devices, becoming activated at the called station requiring the called party to take some action even though that party is involved in another call. Thus a need exists for an arrangement which allows a calling party to become immediately connected to a busy station as soon as the busy station becomes idle without priorly disturbing the busy station.
However, even in situations where the subsequent call is not completed and busy tone is returned, problems exist. Primarily these problems concern the continued attempts on the part of the calling party to place a call to the called busy station or to a called line pool. Much time is wasted by redialing the connection only to find the called station, or line pool, again busy. Some systems have been designed whereby the number of the last dialed call is stored in a memory and periodically retried. However, it often happens that when the originally called party becomes free the original calling party is then busy. Further problems exist in such systems since the calling party must remain close to the calling station so as to be available when the connection is finally established to the called station.
Thus, a need exists in the art for a feature which allows any station in a communication system to determine the busy-idle status of a selected other station served by the same system independent of a communication path to that other station.
There is a further need in the art for such a system of tracking the busy-idle status of selected stations and for receiving a signalling indication when the tracked party goes from the off-hook to the on-hook condition. There is a further need for such a system which operates to establish a communication connection to the tracked station jointly upon receiving such an off-hook to on-hook transition and upon the tracking station going off-hook.
There is also a need for a call tracking arrangement which provides both a visual status and audible determination when a tracked line pool becomes idle and available for use. There is also a need in the art for an arrangement which allows a called station which is in the "don't answer mode" to receive incoming calls immediately upon leaving that mode simply by making an on-hook to off-hook transition.